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Sci Adv. 2018 May 30;4(5):eaar5040. doi: 10.1126/sciadv.aar5040. eCollection 2018 May.

Deglaciation of the Pacific coastal corridor directly preceded the human colonization of the Americas.

Author information

1
Department of Geology, University at Buffalo, Buffalo, NY 14260, USA.
2
Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA.
3
School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.
4
Tongass National Forest, Thorne Bay, AK 99919, USA.
5
Department of Earth Sciences, University of South Dakota, Vermillion, SD 57069, USA.

Abstract

The route and timing of early human migration to the Americas have been a contentious topic for decades. Recent paleogenetic analyses suggest that the initial colonization from Beringia took place as early as 16 thousand years (ka) ago via a deglaciated corridor along the North Pacific coast. However, the feasibility of such a migration depends on the extent of the western Cordilleran Ice Sheet (CIS) and the available resources along the hypothesized coastal route during this timeframe. We date the culmination of maximum CIS conditions in southeastern Alaska, a potential bottleneck region for human migration, to ~20 to 17 ka ago with cosmogenic 10Be exposure dating and 14C dating of bones from an ice-overrun cave. We also show that productive marine and terrestrial ecosystems were established almost immediately following deglaciation. We conclude that CIS retreat ensured that an open and ecologically viable pathway through southeastern Alaska was available after 17 ka ago, which may have been traversed by early humans as they colonized the Americas.

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